Since the earliest days in the development of suitable mouthpieces for an underwater breathing apparatus such as a snorkel, regulator or the like, comfort for the user has been a paramount concern. Numerous designs ranging from the conventional to the exotic have been developed, but almost all diving equipment mouthpieces currently in use are variations of the basic design created by Rouquayrol over one hundred years ago, as disclosed in U.S. Pat. No. 59,529. The mouthpiece therein disclosed includes a vertical flange surrounding the end of the breathing tube and configured to be retained between the teeth and the inside of the lips of the user and a pair of horizontally projecting tabs h,h, situated on either side of the breathing tube opening and gripped by the teeth of the user. 80 years later, the Cousteau-Gagnon "Aqualung" as shown in U.S. Pat. No. 2,485,039, included a mouthpiece which was basically the same as Rouquayrol's.
A similar mouuthpiece designed for use with a respirator employed in a gas medium, rather than a liquid medium, is illustrated in U.S. Pat. No. 1,266,410, issued to Conrad.
Significant variations of this basic mouthpiece design have been developed, but remain relatively unpopular. In one case, the projecting, teeth engaged tabs have been replaced by an oblong or eliptical bite tube surrounding the end of the breathing tube opening, as disclosed in U.S. Pat. No. 2,839,053. A vertical rib may be inserted to prevent collapse of the bite tube when engaged by the teeth, such as is disclosed in U.S. Pat. No. 3,106,916. This particular design has not been widely adopted perhaps because of eventual discomfort to the user. Specifically, the jaws of the user remain pried apart to an unnaturally wide disposition when such a mouthpiece is being used. Additionally this mouthpiece is engaged by the incisors and canines of the user, these being teeth which are not really suited for a load bearing function, rather than the molars which are far better positioned and adapted for a gripping, load bearing function.
Another design never widely adopted was a mouthpiece without any teeth engaged retainer at all, the thought being that a vertical flange between the lips and the teeth would be sufficient to hold the mouthpiece in place while eliminating jaw fatigue. A major problem with this design is that the facial muscles are just too weak to retain the bulk of the mouthpiece comfortably. Thus, excessive facial strain and discomfort soon result.
Improvement of the basic mouthpiece design, such as disclosed by Rouquayrol, has yielded better results. One of the more significant improvements in the art is disclosed and claimed in my prior U.S. Pat. Nos. 3,844,281 and 3,929,548. These patents disclose a mouthpiece having moldable, thermoplastic retainer tabs that are heated to a plastic state and then gripped by the teeth of the user whereupon the material quite readily and permanently conforms to the dental impression of the user. This yields a very comfortable mouthpiece for that user, but such a mouthpiece may subsequently be used only by that user (unless the moldable inserts are replaced). Also, the required initial exercise to custom-fit the retainer tabs to the teeth of the user is a delicate one requiring some skill to accomplish entirely satisfactorily. Furthermore, such a mouthpiece is relatively more expensive than conventional mouthpieces and thus its widespread adoption is resisted by the cost-conscious consumer.
The present invention overcomes these problems by providing a mouthpiece have collapsible retainer tabs that readily conform to an approximate dental impression of the user and thus the mouthpiece will not unduly fatigue the jaws of the user.